Tech Talk | What is Flow Control?

In my last post, I wrote about network addressing, and this week I’m going to be talking a bit about what flow control is in computer networking. Some definitions in here are explained in more detail in my previous posts, so if you want to catch up with the rest of the posts in the Computer Networking series, click here!

What is Flow Control?

Flow control is the management of the transmission of data between two nodes.

Let’s elaborate on that…

Flow control basically ensures that the rate at which data is sent is in proportion to the rate at which the receiver can receive it.

Flow Control is like having customers queue at a fast food restaurant

Imagine a fast food restaurant where customers order food at a till. You go to the tills at the counter, you order what you want and pay, then you wait for your order to come to you.

In this analogy the customers are the senders and the counter would be the receiver: the customers take their orders to the counter and the employee at the counter would receive the order and set about making their food.

So here, the speed of service depends on the amount of employees at the counter to the amount of customers there are: if there are loads of employees and one customer, then great, the order can go through straight away and be completed quickly.

If there are loads of customers and just one employee, then we have a problem. Without flow control in the restaurant, the customers will flood the employee at the counter with their orders, meaning some of their orders might get lost, and that they’ll need to repeat their order.

Flow control in this instance would be having a queuing system, as a way of slowing down the customer ordering for the lone employee to be able to handle it. This is how flow control works in computer networking: the sender rate (if it is faster than the receiver) is slowed to match the receiving rate, so that no data gets lost or needs to be retransmitted.

If you want to check out the rest of the posts in my Tech Talk series, click here. Thank you for reading, and have a wonderful weekend!